JP2021124201A - Joint element, connection structure with joint element, manufacturing method for joint element, and corresponding connection method - Google Patents

Abstract

To pierce and connect high-strength steel components so that debris does not separate.SOLUTION: The present invention relates to a joint element for manufacturing a connection part between at least two components, and comprises a head part at a first axial end part, an end part of a second axial end part opposite to the first axial end part, and a shaft arranged between the end part and the head part, and the shaft defines a longitudinal axis of the joint element between the axial first end part and the axial second end part. The present invention comprises at least an edge layer in which the shaft and end parts of the joint element are hardened, and thus, the materials of the shaft and the end parts have lower hardness inside adjacent to the edge layer, compared to the surface of the edge layer.SELECTED DRAWING: Figure 4

Description

The present invention relates to a joining element for connecting between at least two components, a connecting structure comprising at least the first and second components and connected by the joining element, a method of manufacturing the joining element, and at least the first by the joining element. The present invention relates to a method for connecting one component to a second component.

Joining elements for establishing a connection between two components typically include a head, a shaft, and an end. The specific structure of the joining element depends on the desired field, and as a result, the joining element is known in the prior art in a number of different designs.

For example, DE 10 2010 025 359 A1 describes at least one non-pre-punched part with a nail as a joining element for axially driving essentially non-rotating. The nail as a joining element includes a nail head, a nail shaft, and a nail tip, which in some parts include a surface profiling. The surface profiling of the portion has a lower hardness than the nail shaft, depending on its radial depth.

Setting bolts are disclosed in DE 10 2014 019 322 A1 as additional connecting elements for connecting at least two components. The connecting element comprises a pointed portion and a shaft portion having different properties, and the connecting element is formed as an integral body. For example, the pointed portion has higher strength than the shaft portion.

DE 103 28 197 B3 relates to fastening elements such as bolts or nails. The fastening element includes a shaft, the tip of which is arranged at one end of the shaft and the head of which is arranged at the other end. The fastening element includes a core zone of relatively hard carbon-containing steel and a ferrite edge zone of low carbon steel having a lower hardness. A transition zone is arranged between the shaft and the tip, and the thickness of the ferrite edge zone gradually decreases from the shaft to the tip to a value close to zero.

Additional fastening elements are described in DE 10 2007 000 485 B3. The fastening element comprises an inner core zone of a relatively hard carbon-containing steel and an outer edge zone alloyed with a first alloyed metal of a first austenitic steel having a lower carbon than the core zone. Between the core zone and the peripheral zone, at least one first intermediate zone of the second low carbon steel is arranged, which has a lower hardness than the steel of the core zone.

Finally, US 2003/014260 A1 also discloses fastening elements. This fastening element includes a first tip bearing shaft portion that has greater hardness compared to the subsequent second shaft portion.

German Patent Application Publication No. 10 2010 025 359 German Patent Application Publication No. 10 2014 019 322 German Patented Invention No. 103 28 197 German Patented Invention No. 10 2007 000 485 U.S. Patent Application Publication No. 2003/014260

With known joining elements, components made of materials with tensile strengths of up to 600-800 MPa can now be reliably joined within the range of high speed bolt setting. Starting from this strength class, debris separation and / or joint element breakage occurs. Thus, known joint elements are damaged when the joint is translatorily set to a component of high-strength or ultra-high-strength steel that has not been pre-punched, and the tip of the joint completes the component. Should penetrate.

Therefore, the subject of the present invention is to realize single-sided joining of components made of high-strength steel or ultra-high-strength steel having a tensile strength in the range of more than 800 MPa in a one-step process without damage to the joining elements and separation of slag. It is to provide a joining element that can. Further, an object of the present invention is to provide a corresponding connection structure, a method for manufacturing a joining element, and a method for connecting two components.

The above-mentioned problems are the joining element according to the independent claim 1, the connection structure according to the independent claim 6, the method for manufacturing the joining element according to the independent claim 8, and at least the first item according to the independent claim 13. It is solved by a method of connecting a component to a second component. Advantageous embodiments and further developments arise from the following description, drawings, and appended claims.

The joining element of the present invention is provided at the head of the first axial end and the second axial end opposite to the first axial end in order to realize a connection between at least two components. A shaft is provided between an end portion and the end portion and the head portion, and the shaft is provided in the longitudinal direction of a joining element between the axial first end portion and the axial second end portion. An axis is defined and at least the shaft and the end of the joining element include a hardened edge layer, so that the material of the shaft and the end is on the surface of the edge layer in the interior adjacent to the edge layer. Has a lower hardness than that.

As such, the joining elements of the present invention include known heads, shafts, and ends. Preferably, in particular, the end and the shaft are integrally formed. It is particularly preferred that the joining element be formed as a whole, i.e., the head, shaft, and ends in one component. Similarly, the joining element is preferably composed of only one material. This is especially true for shafts and ends.

The extension of the shaft between the head and the end also defines the longitudinal axis of the joining element between the first axial end and the second axial end in the usual way. It is also called the central axis in the longitudinal direction depending on its position and course. Preferably, the shaft is formed in a cylinder shape.

In addition, the bonding elements of the present invention include a hardened edge layer. The advantages of this hardened edge layer are described below based on the setting bolt as the joining element. In this regard, the joining element is preferably selected from the group including the following setting bolts, semi-hollow self-perforated rivets, solid self-perforated rivets, blind rivets and screws.

After the joining element is manufactured by conventional methods, such as cold forming, the edge layer of at least the shaft and ends, preferably the entire joining element, such as a setting bolt, is cured in a further processing step. Depending on the raw material or material of the joining element, high edge hardness of up to 1,200 HV 10 can be achieved, while at the same time providing a "soft and ductile" interior. Therefore, the shaft does not change internally, especially with respect to the setting bolts that illustrate the joining elements. In this context, a hardness of 1,200 HV 10 represents a Vickers hardness (HV) of 1,200 Vickers hardness (HV) with 10 kilopounds of test force or applied force.

The advantage of these edge layer hardened joint elements is that the joint element, eg, setting bolts, is set on a component made of high-strength or ultra-high-strength steel. Therefore, the bonding elements of the present invention exceed 800 MPa, preferably more than 1,200 MPa, particularly preferably up to 2,000 MPa, or at least 1,500 MPa, without separating debris and without deforming the ends. It can be placed in a component made of steel with a tensile strength of up to.

In addition to the expanded process window, the notch bar impact output and ductility are also increased. This is due to the softness of the interior of the joining element as opposed to the hardened edge layer. The notched bar impact work or notched bar impact strength is a measure of the sudden and / or dynamic stress of the joining element. This stress occurs not only during the joining process, but also in later connecting structures if the joining elements must hold at least two components under load together. Thus, for example, this increased notch rod impact output or notch allows for large temperature differences during further processes of the connection, or mechanical loads on the connection structure, without any adverse effects on the connection. The bar impact strength has an advantageous effect on the connections made by the joining elements.

In an advantageous embodiment of the joining element, at least the shaft and end materials are hardened and hardened. In this way the hardness of the edge layer can be further increased over non-quenched and non-tempered materials, depending on the procedure used to create the edge layer. Quenching Tempering refers to a combined heat treatment of a metal such as steel, which consists of quenching and subsequent tempering. Therefore, a prerequisite for quenching and tempering is the hardening performance of the steel used, i.e. the ability to form a stable martensite or bainite structure under certain conditions. For hardening itself, it is first necessary to heat the steel material quickly above the austenitizing temperature. The steel is then quenched, i.e. the heated material is rapidly cooled by using a quenching agent, preferably water, oil (polymer bath) or air. Finally, a tempering or blue-annealing process is performed, which is a heat treatment in which the steel is specially heated to affect its properties, especially to reduce stress.

Further, curing of the edge layer is preferably achieved by nitriding, curing by high frequency, curing by flame, curing by laser light, curing by electron beam or carburizing. Here, as the nitriding, gas nitriding is particularly preferable. Nitriding in particular allows the bonded element to be cured to be treated as a bulk material, which provides an economical treatment method in addition to advantageous treatment times.

Another preferred embodiment of the joining element comprises coating at least the shaft and the ends of the joining element, preferably the entire joining element, with a material that is harder than the material of the shaft and the ends. Instead of using the material of the joining element, a separate coating is used here to produce a hardened edge layer. The resulting technical effect preferably already corresponds to the technical effect described above.

The connection structure according to the present invention includes at least a first component and a second component, and these components are connected by the joining element according to the present invention. Therefore, with respect to the resulting benefits and technical benefits, refer to the above description of the joining elements of the present invention to avoid unnecessary repetition.

In a preferred embodiment of the connection structure, the first component is placed adjacent to the head, the second component is placed adjacent to the end of the joining element, and the second component is at least 800 MPa. It is composed of steels having tensile strengths, particularly between 800 MPa and 2,000 MPa, or at least 800 MPa and 1,500 MPa, especially hot-formed steels. The particular design of the joining element of the present invention, which has an outer hard edge portion and a softer core, ensures that debris is not separated from a second component made of steel with a tensile strength of at least 800 MPa. This is to ensure. In this way, unfavorable noise generation is also avoided.

The method for manufacturing a joining element according to the present invention includes the following steps, in particular, a head provided at the first axial end portion by cold forming or turning and an axial direction opposite to the first axial end portion. It is arranged between the end provided at the second end and the end and the head, and defines the longitudinal axis of the joining element between the first axial end and the second axial end. At least the shaft and end of the joint element is cured so that the shaft and end have a hardened edge layer with the step of providing the joint element with the shaft, whereby the material of the shaft and end is compared to the surface. The step comprises a step having a lower hardness inside which is adjacent in the radial direction. The joining element of the present invention described above is manufactured according to the manufacturing method of the present invention. Therefore, refer to the above description to avoid repetition with respect to the benefits and the resulting technical benefits.

A preferred embodiment of the manufacturing method comprises quenching and tempering at least the shaft and ends of the joining element prior to the step of curing the joining element. The advantage of this procedure is that the hardness of the subsequent edge layer can be further increased compared to the bonding elements of non-quenched and non-tempered materials, especially when using methods such as nitriding.

Preferred manufacturing methods also include nitriding, curing by high frequency, curing by flame, curing by laser light, curing by electron beam, or carburizing, or curing by coating at least the shaft and ends of the bonding element. See above for the advantages of each method.

Advantageous materials for joining elements include cold formable steel. In this way, for example, setting bolts can be cost-effectively manufactured as cold-formed joint elements.

The connection method of the present invention in which at least the first component is connected to the second component by a joining element includes a step in which the first and second components are arranged one above the other and the first and second components. It is preferred that the setting of the joining elements is performed essentially non-rotating, comprising the step of setting the joining elements in the arrangement in which the members are arranged one above the other. An essentially non-rotating setting can be described as an exclusively translational setting for the joining elements. This setting is performed on components where the joints are not pre-punched and should be connected to each other. At the end of the setting process, depending on the joining element used, the ends of the joining element preferably penetrate both components, but at least the components facing the head. For the resulting benefits, refer to the above description of the joining elements of the invention to avoid repetition.

Preferably, the first component is placed adjacent to the head, the second component is placed adjacent to the end of the joining element, and the second component has a tensile strength of at least 800 MPa, particularly 800 MPa. It is composed of steel having a tensile strength of about 2,000 MPa or at least 800 MPa to 1,500 MPa, particularly hot-formed steel. As explained at the beginning, in the case of such a component, there is a risk of plastic deformation at the end of the joining element. This risk is minimized or preferably eliminated due to the hardened edge layer.

In a preferred embodiment of the method, the first component is placed adjacent to the head, the second component is placed adjacent to the end of the joining element, and the penetration of the second component is punched debris. Is done without separation. The special setting of the outer hard edge portion of the joining element of the present invention and the softer core material allows debris not to be separated from the second component made of steel having a tensile strength of at least 800 MPa. That is. In this way, unfavorable noise generation is also avoided.

It is sectional drawing of the joining element. It is a perspective view of the joining element set in the component made of high-strength or ultra-high-strength steel. It is a perspective view of the joining element set in the component made of high-strength or ultra-high-strength steel. It is a perspective view which set the joining element which concerns on one Embodiment of this invention on a part made of high-strength or ultra-high-strength steel. FIG. 5 is a photomicrograph or a cross-sectional view of a microscope showing an end portion of a joining element according to an embodiment of the present invention. It is a graph for demonstrating the hardened edge part. It is a graph of hardness and notch bar impact output. It is a flowchart which shows one Embodiment of the manufacturing method of the joining element of this invention. It is a flowchart which shows one Embodiment of the method of this invention which connects two components by a joining element.

With reference to FIG. 1, the joining element 1 is shown in the form of a setting bolt. See DE 10 2006 002 238 A1 for details of the shape, the contents of which are incorporated as references in this regard.

Semi-hollow self-perforated rivets, solid self-perforated rivets, blind rivets, screws, etc. can also be used as the joint elements instead of the setting bolts as the joint element 1, and the following description applies depending on these joint elements. Will be done. For shape details, DE 10 2012 102 860 A1, DE 10 2015 118 888 A1 and DE 10 2019 102 383 A1 for semi-hollow self-perforated rivets, DE 10 2018 128 455 and DE 10 2019 for solid self-perforated rivets. See 102 380 and DE 20 2005 005 536 U1 and EP 1 710 454 A1 for blind rivets.

With reference to FIG. 1 again, the joining element 1 is arranged in a known manner with the head 10 at the first axial end, the end 20 at the tip in the present embodiment at the second axial end, and between. The shaft 30 is provided. The shaft 30 defines the longitudinal axis L of the joining element 1 between the first axial end and the second axial end, which is also referred to as the longitudinal central axis because of its position. can.

The head portion 10 of the joining element 1 includes a flat upper side 12, a cylinder-shaped circumferential surface, and a flat lower side surface 14. The flat underside 14 has an annular groove 16 adjacent to the shaft 30 to accommodate the accumulation of beaded or bulge-like material of the head side components, which makes the joint element 1 into at least two components. It is especially advantageous when setting.

The annular groove 16 has a rounded circumferential surface adjacent to the shaft 30, one of which smoothly transitions to the shaft 30 in the tangential direction of the roundness and the other of which transitions to a conical surface. In this way, especially when the material of the component facing the head rises with respect to the joining direction, the material can be accommodated in the annular groove 16.

The shaft 30 is formed in a cylinder shape and preferably has, at least in part, a surface profiling 32 for receiving the material of component A facing away from the head. In this way, the joining element 1 is particularly reliably fixed to at least one component.

The end 20, the tip in this embodiment, is directly adjacent to the shaft 30.

Next, the drawbacks of known joint elements will be described with reference to FIG. 2, which shows a perspective view of the joint element set in the component made of high-strength steel or ultra-high-strength steel. The joining element used comprises a hardness of 450 HV 10, i.e. 450 Vickers hardness (HV) with a test force or applied force of 10 kiloponds. Due to the high tensile strength of components made of high-strength steel or ultra-high-strength steel, the use of known joining elements results in plastic deformation of the end 22 of the joining element. In addition, the debris 40 is separated from the components. However, this is disadvantageous for improving noise, even if the components can only be accessed from one side. Therefore, as a whole, connections made in this way are classified as unacceptable.

FIG. 3 shows a perspective view of another joining element set in a component made of high-strength steel or ultra-high-strength steel. The joining element used here comprises a hardness class 8 having a hardness of 600 HV 10. Increasing the hardness of the joining element not only increases brittleness, but also reduces deformation of the edges. As can be seen from FIG. 3, the debris remains in the through hole. In this case, especially dynamic loads can cause loosening of debris. This in turn causes damage to the cathode immersion coating layer, especially in the manufacture of automobile bodies, so that the corrosion protection of this portion is lost when the component is further processed by the bonding element. Therefore, this connection is unsuitable and disadvantageous for further processing steps or post-process processing steps.

By the way, referring to FIG. 4, a perspective view in which the joining element according to the embodiment of the present invention is set in a component made of high-strength steel or ultra-high-strength steel is shown. Therefore, at least the shaft and the end portion of the joining element preferably include the cured edge portion 24 as the whole joining element. The use of the cured edge portion 24 makes it possible to achieve a hardness of up to 1,200 HV 10, depending on the material used for the joining element.

FIG. 5 shows a micrograph or microscopic cross section of the end 20 of the joining element to show the material change. Curing of the edge portion 24 was achieved by nitriding, especially gas nitriding. Apart from nitriding, a method of further treating the provided joining element as a bulk material is preferred, i.e. a method which does not require individual treatment of the joining element is preferred.

As can be seen from FIG. 5 in relation to FIG. 6, the cured edge portion 24 extends to the interior of the joining element to a depth of about 1.2 mm. The hardness curves or progressions of the two bonding element materials 34Cr4 and 42CrMo4 are shown in FIG. Nitriding cures these materials to 900 HV 0.3, with such hardness decreasing linearly towards the core. The nitriding depth, that is, the depth of the cured edge layer 24 is surely adjusted by the nitriding time.

By using a joining element with a hardened edge layer, debris does not peel off from a steel material having a tensile strength of 1,200 MPa, and joining is possible without deformation of the end portion. In addition, steels such as hot-formed steels having a tensile strength of up to 2,000 MPa, for example 1,500 MPa, can be joined to a thickness of about 1.2 mm.

In addition to the expansion of the process window when setting the joining elements, the notch bar impact output is increased, thus increasing ductility. The notched bar impact work or notched bar impact strength is a measure of the sudden and / or dynamic stress of the joining element. This stress occurs not only during the joining process, but also when the joining elements hold at least two components together under the load of the components in the subsequent connection structure. This increased notch bar impact output or notch bar impact strength is due to the core 26 inside the joint element 1, which is softer than the hardened edge portion 24. For example, by changing the material from C67 to 34Cr4 and using a nitriding process, the notch rod impact output can be increased 10-fold, as shown in FIG. 7, taking into account different materials.

One of the advantages of this attribute affects the later connection structure. The combination of a hard edge and a relatively soft core results in a secure fixation of the joining element in subsequent processing steps, despite the hardened edge. This applies, for example, to the artificial passage of time after the two components joined by the joining element.

The connection structure in which the joining element is used is composed of, for example, a first component facing the head and a second component away from the head. The components are connected by embodiments of the joining elements of the present invention. Here, the ends of the joining elements can penetrate both components. Alternatively, the ends of the joining elements are placed within the component facing away from the head. Similarly, the joining element can be set to only one of the components and then welded to the second component.

Preferably one of the components, especially the component B away from the head, is made of steel having a tensile strength of at least 800 MPa. As a result, the component B away from the head, or the lower component B, is made of high-strength or ultra-high-strength steel. Due to the particular design of the joint element, the risk of fracture of the joint element and plastic deformation of the end 20 sets the joint element within component B as it would when penetrating component B, as described above. Sometimes it is reduced or preferably eliminated. In addition, the joining element prevents debris from being separated or cut from a second component made of steel having a tensile strength of at least 800 MPa.

FIG. 8 shows a flowchart of an embodiment of a method for manufacturing a joining element. The joining element is preferably composed of at least a steel capable of cold forming the shaft and ends. Further, the coupling element is advantageously selected from the following groups of setting bolts, semi-hollow self-perforated rivets, solid self-perforated rivets, blind rivets, screws and the like.

In the manufacturing process, in the first step A, especially by cold forming or turning, the head is at the first axial end and at the second axial end opposite to the first axial end. A joint element having an end and having a shaft disposed between the end and the head is created, and in the step of creating the joint element, the shaft has an axial first end and an axial first. The longitudinal axis of the joining element is defined between the two ends.

In any step C, at least the shaft and ends of the junction element, preferably the entire junction element, are quenched and tempered. For details of quenching and tempering, refer to the above description.

In the final step B, at least the shaft and end of the joint element, preferably the entire joint element, is cured, thereby providing a hardened edge layer on the shaft and end, and the material of the shaft and end is compared to the surface. Has low hardness inside adjacent to the radial direction. The curing step includes either nitriding, curing by high frequency, curing by flame, curing by laser light, curing by electron beam or carburizing (step D1), or the curing step coats at least the shaft and end of the joining element. (Step D2) In this way, the joining element of the present invention described above is manufactured as an embodiment.

Finally, FIG. 9 shows a flowchart of an embodiment of a method of connecting the first component A to the second component B by the joining element of the embodiment. In the first step I, the first component A and the second component B are arranged one above the other. In the next second step II, the joining elements are set with respect to the arrangement of the first and second components arranged one above the other, and the setting of the joining elements is essentially non-rotating. An essentially non-rotating setting can also be described as a mere translational setting of the joining elements.

The first component is placed adjacent to the head, the second component is placed adjacent to the tip of the joining element being set, and the connection between the two components is pre-strike as previously described. Not pulled out. The second component is particularly composed of steel having a tensile strength of at least 800 MPa. Penetration of the second component B is done without debris separation. The unique design of the joining elements of the present invention makes it possible that debris is not separated from the second component made of steel with a tensile strength of at least 800 MPa.

1 Joining element
10 head
12 upper side
14 Bottom surface
16 annular groove
20 ends
22 Plastic deformation end
24 Hardened edge layer
26 cores
30 shaft
32 Surface profiling
40 Fragment A Component L Longitudinal axis.

Claims (15)

The head at the first end in the axial direction and
The end at the second end in the axial direction opposite to the first end in the axial direction,
A shaft disposed between the end and the head and defining a longitudinal axis of the joining element between the axial first end and the axial second end, at least two. In the joint element for manufacturing the connection between the components,
Of the joining elements, at least the shaft and the end portion include a hardened edge layer, and the material of the shaft and the end portion has a low hardness inside adjacent to the edge layer as compared with the surface of the edge layer. A joining element, characterized by having. The joining element of claim 1, wherein at least the shaft and the material at the end are quenched and tempered. The joining element of claim 1 or 2, selected from the group consisting of setting bolts, semi-hollow self-perforated rivets, solid self-perforated rivets, blind rivets and screws. The bonding element according to any one of claims 1 to 3, wherein the edge layer is cured by nitriding, curing by high frequency, curing by flame, curing by laser light, curing by electron beam, or carburizing. The joining element according to any one of claims 1 to 3, wherein at least the shaft and the end of the joining element include a coating of a material having a hardness higher than that of the material of the shaft and the end. A connection structure comprising at least a first component and a second component connected by the joining element according to any one of claims 1-5. The first component is placed adjacent to the head, the second component is placed adjacent to the end of the joining element, and the second component is steel, especially hot. The connection structure according to claim 6, which is composed of molded steel and has a tensile strength of at least 800 MPa, particularly a tensile strength of 800 MPa to 2,000 MPa, or a tensile strength of at least 800 MPa to 1,500 MPa. The method for manufacturing a joining element according to any one of claims 1 to 5.
In particular, by cold forming or turning, the head is located at the first axial end, the end of the second axial end opposite to the first axial end, and between the end and the head. The head has an arranged shaft and supplies the joining element, which defines a longitudinal axis of the joining element between the axial first end and the axial second end a. Steps and
At least the shaft and the end of the joining element are hardened so that the shaft and the end include a hardened edge layer, whereby the material of the shaft and the end is radially adjacent relative to the surface. A method of manufacturing a joining element, comprising a b-step having a low hardness inside. Before the b step of curing the joining element,
The manufacturing method according to claim 8, further comprising a c-step of quenching and tempering at least the shaft and the end of the joining element: The b step is
Includes or includes nitriding, high frequency curing, flame curing, laser beam curing, electron beam curing or carburizing.
The manufacturing method according to claim 8 or 9, wherein at least the shaft and the end portion of the joining element are coated. The production method according to any one of claims 8 to 10, wherein the joining element is selected from the group consisting of setting bolts, semi-hollow self-perforated rivets, solid self-perforated rivets, blind rivets and screws. The production method according to any one of claims 8 to 11, wherein the material of the joining element includes cold-formable steel. A method of connecting at least the first component to the second component by the joining element according to any one of claims 1 to 5.
The step of arranging the first and second components one above the other,
A connection method characterized in that the joining element is set in the arrangement of the first and second components arranged one above the other, and the setting of the joining element is performed essentially without rotation. The first component is placed adjacent to the head, the second component is placed adjacent to the end of the joining element, and the second component has a tension of at least 800 MPa. 13. The method of claim 13, comprising steel having a strength, particularly a tensile strength of 800 MPa to 2,000 MPa, or a tensile strength of at least 800 MPa to 1,500 MPa, particularly hot-formed steel. The first component is placed adjacent to the head, the second component is placed adjacent to the end of the joining element, and the penetration of the second component is a punched debris. 13. The method of claim 13 or 14, which is carried out without separation.

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